In recent years, energy-assisted magnetic recording has been proposed as one technique for increasing recording density of a hard-disk drive (HDD). Energy-assisted magnetic recording is a technique in which a magnetic-recording field is applied to a magnetic-recording disk along with near-field light, microwave radiation, or alternative means of magnetic-recording assistance. Also, in recent years, recording density in HDDs has remarkably increased, and correspondingly, the size of the magnetic pole of the magnetic-recording head used in a HDD has been reduced. However, since the magnetic-recording field generated by the magnetic-recording head depends on volume of a magnetic pole that performs the write operation, maintaining the intensity of the magnetic-recording field has become difficult, because the intensity of the magnetic-recording field has decreased along with the reduction in size of the magnetic pole.
As is known in the art, a pole tip of a main pole that generates a magnetic-recording field may be formed with a trapezoidal shape where a width on a leading-edge side (LD side) is narrower than a width on a trailing-edge side (TR side) to prevent recording error on an adjacent track, referred to by the term of art, “side erasure,” associated with perpendicular-magnetic-recording (PMR) heads. However, when fabricating the width of the main pole as described above, the volume of the main pole is reduced, so that maintaining the intensity of the magnetic-recording field becomes more difficult. Similarly, maintenance of the magnetic-recording field strength is also an issue for energy-assisted magnetic recording.